Balancing Rations. Animal Science II Unit 8. Classifying Rations. Roughages M ore than 18% crude fiber when dry Hard to digest Include: hay, silage, pasture, fodder* 2 classes: Legume and Non-legume Legumes*
Animal Science IIUnit 8
Ration-the amount of feed given to an animal in a 24 hour period
Balanced ration-a ration that has all the nutrients needed in the proper proportions.
Must be palatable, balanced for species, age, and function
Ration must meet the needs of the animal
Nutrient allowance should be met as closely as possible and not more than 3% below.
Ration must contain a certain amount of dry matter
Digestible Energy (DE)
Total Digestible Nutrient (TDN)
Metabolizable Energy (ME)
Net Energy (NE)
See fig 8-1
2,000 pounds of feed is needed to feed a 100 pound growing hog. A feeding standards table shows that a 14% crude protein ration is needed. Corn and soybean meal are selected as feeds. A feed composition table shows that corn is 8.9% and soybean oil meal has a 45.8% crude protein on as-fed basis. How much corn and how much soybean meal is needed to be mixed together for 2,000 pounds of feed.
Draw a square with lines connecting the opposite corners. Write the percent of crude protein needed in the center of the square.
Write the feeds to be used and their crude protein percents at the left hand corners of the square.
Soybean Meal 45.8
Subtract the smaller number from the larger along the diagonal lines. Write the difference at the opposite end of the diagonals.
To check to ensure that the square is setup correctly find the sum of the numbers on the right should equal the difference of the numbers on the left.
Divide the parts of each feed by the total parts to find the percent of each feed in the ration.
Corn 31.8/36.9 x 100= 86.2%
SBM 5.1/36.9 x 100= 13.8%
It is known that 2,000 pounds of the mixture is needed. However, we need to know how much of each grain is needed to make the 2,000 pound mixture. This done by multiplying the percent of corn in the mix by the total pounds of the mix.
2,000 x 0.862= 1,724 lbs of corn
2,000 x 0.138= 276 lbs of soybean meal
Check the mix to make sure the protein need is met.
1,724 lbs of Corn x 0.089= 153 lbs of corn protein
276 lbs of SBM x 0.458= 126 lbs of soybean protein
153 + 126= 279 pounds of protein total
279/ 2,000 x 100= 14%
The mix is balanced for crude protein!
Assume that a 2,000 pound mix of corn, oats and soybean meal is needed. The mix is to contain 16% digestible protein. A decision is made to use ¾ corn and ¼ oats in the mix. Thus the proportion of corn to oats is 3:1. How many pounds of corn, oats, and soybean meal are needed?
The weighted average percent protein in the corn and oats is found first. Multiply the proportions of corn by the percent digestible protein in the corn. Do the same for oats. Add the two answers together and divide by the total parts. The answer is the weighted average percent of digestible protein in the corn-oats mix.
Corn 3 x 7.1= 21.3
Oats 1 x 9.9= 9.9
31.2/4= 7.8% digestible protein in the corn-oats mix.
You then use the Pearson Square as in you did in example 1.
3 parts corn plus 1 part oats 7.8
25.7/33.9 x 100= 75.8% corn-oat mix
8.2/33.9 x 100= 24.1% SBM
0.758 x 2,000= 1516 lbs corn-oat mix needed
1516 lbs x .75 (3/4)= 1,137 lbs of corn needed
1,516 lb x .25 (1/4)= 379 lbs of oats needed
.241 x 2,000= 482 lbs soybean meal needed
Check the mix.
1516 x .078=118.2
200.9 + 118.2= 319.1
319.1/2,000= 0.159= 16%
The ration is balanced for digestible protein.